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0409 PD: New Johne’s vaccine will offer more protection, fewer side effects

Karen Lee Published on 25 February 2009

A new vaccine developed by scientists at Cornell’s College of Veterinary Medicine aims to provide better prevention of Johne’s disease with fewer side effects than the current vaccine on the market.

Johne’s disease is a contagious, chronic and usually fatal bacterial infection that mainly infects the small intestine of such ruminants as cattle, sheep and goats as well as farm-raised deer, elk, llamas, alpaca, bison and zoological wildlife.

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“Johne’s disease is one of the most important infectious diseases that threatens farmers,” said Yung-Fu Chang, Cornell professor of microbiology and the paper’s lead author.

The disease is caused by the Mycobacterium avium subspecies paratuberculosis, a hardy bacterium known to survive for up to a year in the outside environment. Found worldwide, the bacterium causes a thickening of the intestinal wall that blocks the normal absorption of food. Infected animals eat normally but cannot absorb any nutrients, which results in wasting and death.

To date, only one vaccine is commercially available in the U.S. It is made from killed M. paratuberculosis and is produced by Fort Dodge Animal Health and sold by Solvay Animal Health under the trade name Mycopar.

The Cornell team, led by Chang, identified new targets and antigens to develop this vaccine. Their antigen is licensed to the Biotechnology Research and Development Corp.

“Like any vaccine it works by stimulating the body’s own organisms to recognize and attack,” says Dr. Bruce Akey, director of the Animal Health Diagnostic Center at Cornell University.

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Animals infected with Johne’s disease shed the bacteria in their manure and spread the disease. Other animals get infected through contaminated feed or water. Newborns and young animals can catch the disease through contaminated teats or directly from an infected mother’s colostrum or milk. Unborn calves are also at risk of infection while in the uterus of an infected cow.

This new vaccine will work to prevent the animal from getting infected in the first place, stop the disease from running rampant in the animal if it should become infected, and/or prevent the bacteria from multiplying and spreading to other animals on the farm.

“The vaccine currently out on the market doesn’t stop infection,” Akey says. However, “it does prevent damage to the animal and reduces shedding.”

“I think this new vaccine will do a better job of all three,” he adds.

Akey also predicts this new vaccine will not have the same complications as the one that is currently available to producers. “By refining the vaccine and selecting different kinds of antigens, I think we’ll have less side effects,” he says.

According to the Johne’s Information Center website, hosted by the University of Wisconsin-Madison, “The vaccine [Mycopar] used in the U.S. is a mixture of killed mycobacteria and oil. It can sometimes cause large lumps at the site of injection, usually the brisket region. Occasionally these lumps will become draining abscess-like lesions. Although the vaccine is given to calves less than 30 days old, the tissue reaction at the injection site may last for the life of the animal.”

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Lesions can also form on humans if accidental injection occurs.

“We haven’t seen these lesions in laboratory animals,” Akey says. However, this vaccine has yet to undergo testing on cattle.

“The existing vaccine is not all bad,” he notes. Akey knows of a dairy in New York where it’s been very effective in combination with changes in management practices.

“Before this new vaccine reaches the market, a vaccine company will have to test it on cattle,” he adds.

Akey mentions there is a company that has expressed interest in this new vaccine. It will further develop the vaccine and take the steps to have it licensed by the U.S. Department of Agriculture – a process that can take two to five years to happen.

Before the vaccine can be released to producers the company must prove the safety of the vaccine and its efficacy. According to Akey, they have this information from a laboratory setting, but the company will need to provide field data.

“Even with a better vaccine, it’s still just a tool in Johne’s disease management,” Akey says. “You still have to make management changes to stop it from spreading. We can’t solve this disease just with a vaccine.”

Management changes recommended by the Johne’s Information Center include:

Cows should calve on clean pastures or in clean and disinfected maternity pens

Use colostrum only from Johne’s test-negative cows

Feed artificial milk replacer or pasteurize waste milk fed to calves until weaning

Follow common sense farm sanitation practices to avoid manure contamination of feed and water.

Test for Johne’s disease once a year and cull test-positive cows at the end of their lactation. PD

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